1. Field of the Invention
The invention relates to energy conversion in wheeled vehicles, and particularly to an apparatus for converting energy in turning wheels of a vehicle by means of hydraulic machinery.
2. Description of the Related Art
Conventional wheeled vehicles are driven by gasoline or electric engines. The higher the mass of the vehicle, the more energy is required to drive them. However, some energy inputted to drive wheeled vehicles can be recovered during vehicle movement.
For example, Chinese Pat. ZL 00257350.4 discloses a wheel power assisted device comprising a tooth ring disposed on a wheel rim and having inner teeth of more than one loop, two or more transmission gears, a center gear, a wheel rim, and a gear mounting plate. The impact force generated by the rotation of wheels is transformed into the driving force that drives the wheels to rotate, so as to assist in increasing the rotating speed of the wheels. However, the impact force generated by the rotation of the wheels is too small to be of practical use.
Chinese Pat. No. ZL9216608.X discloses a wheel power assisted device comprising a mounting plate, a plurality of pressure cylinders annularly disposed on the mounting plate, a clutch, a hydraulic fluid reservoir, a hydraulic fluid-inlet pipe, and a hydraulic fluid-outlet pipe. As the wheel rotates, the annularly disposed pressure cylinders are compressed when the wheel is contacted with the ground, and drive a power cylinder piston and transmit force to the clutch. The clutch then forces the wheel to rotate. The structure is complex and energy losses after multiple transmissions are significant. Moreover, it is difficult to attain a high-speed reciprocating movement of the pistons, and especially a simultaneous movement of two cylinders, and therefore the overall energy recovery is relatively low. Finally, the inclined position of the hydraulic fluid reservoir leads to a decreased balance during rotation of the wheel, and a large number of interconnected pipes reduces reliability.
Chinese Pat. No. ZL99205764.7 discloses a hydraulic power-assisted device comprising a hydraulic fluid reservoir, a hydraulic pump, a one-way valve, an accumulator, a switch, a safety valve, a hydraulic fluid-pipe, and a plurality of annular strengtheners. The annular strengthener disposed on a wheel rim comprises a plurality of hydraulic fluid cylinders annularly arranged at an angle to a vertical line of the wheel shaft, and an eccentric disk fixed on the wheel shaft and a hydraulic fluid-pipe. With the gravity of a vehicle and given the barrier of the eccentric disk, a piston pushes the cylinder backwardly and causes the wheel to rotate while extracting energy. However, since the device uses an external hydraulic fluid-reservoir and extra pipes are connected to an annular hydraulic strengthener, the solution is relatively complex, the number of accessories is large, the reliability is poor, and the loss of hydraulic fluid is great. Moreover, the backward push of the wheel by the cylinder not only makes the structure complex, but also does not allow for a high-speed transfer. Finally, the externally-connected hydraulic fluid pump consumes relatively high-amount of energy.
In sum, conventional annularly-arranged hydraulic cylinder devices generate hydraulic fluid pressure by compressing a hydraulic plunger during the rotation of wheels, drive hydraulic components, so as to extract energy and apply driving force to rotating wheels whenever necessary, but have the disadvantages such as complex structure, difficult applicability to multiple wheels, and high manufacturing and assembly cost. In addition, the cost requirement of externally-disposed hydraulic fluid reservoir is comparatively high, and multiple rotary seals are needed. Therefore, much opportunity for improvement remains.